1. Field of the Invention
The present invention relates to building curtain walls and, more particularly, but not by way of limitation, to methods of and apparatus for constructing, assembling and sealing vertical mullions and horizontal members sections of such curtain walls along with the curtain wall panels associated therewith.
2. Description of the Related Art
The advantages of building curtain wall technology are well known and accepted in the industry. Curtain walls are typically constructed of extruded aluminum frame support members having generally U-shaped channels (although other shapes may apply) for supporting a plurality of panel members that serve as the exterior of a building. Such panel members are most often panes of glass, and often double pane glass sections, but other paneled building materials such as aluminum, granite, slate, or concrete are also utilized. Such panel members are often of identical size and shape. However, near doors, opening windows, or other access points into the building, panel members of different sizes and shapes may be utilized.
More specifically, such curtain walls generally include a horizontal member having at least one portion forming an upwardly facing region (or channel) at the bottom of a wall section, a horizontal head member having a downwardly facing channel at the top of a wall section, and a plurality of vertical members running between the horizontal member and head members. Panel members are supported by the channels of the horizontal member and the head member, and the vertical joints between adjacent panel members are formed at the members. In some designs, the mullions are disposed interiorly of the horizontal member, the head member, and the panel members so that only the joint between adjacent panel members, and not the mullions themselves, are visible from the exterior of the building. The designs do, however, vary, depending upon the desired aesthetics of the curtain wall construction.
One such design is set forth and shown in U.S. Pat. No. 4,899,508, assigned to the assignee of the present invention. The '508 patent describes a building system integrating the combination of aluminum and steel structural elements for the efficient assembly of stone and glass panels in a curtain wall system. A plurality of discrete steel clips are utilized for securing stone panels to supporting mullions. A plurality of aluminum members are secured to structural mullions whereby glass may be mounted thereto. The stone and glass panels are sealably secured adjacent one another while a glazing adapter is constructed for assembly over the structural mullions therebehind. A splice facilitates mating engagement of the aluminum mullions to permit relative movement therebetween.
Another curtain wall construction is set forth and shown in U.S. Pat. No. 6,158,182, also assigned to the assignee of the present invention. As set forth in the '182 patent, multiple panel members are typically arranged side-by-side and are secured and sealed between a horizontal member and a head member, with their vertical joints overlapping at a mullion. This vertical joint is sealed from both the interior and exterior of the building using both resilient gaskets, sealing tapes, sealant, and/or structural silicone, as described for reference purposes below.
Referring now to FIG. 1, a schematic, cross-sectional view of a horizontal member 10 of an exemplary curtain wall is shown. The horizontal member 10 secures a curtain wall to a structural support surface such as a concrete slab 12. The concrete slab 12 may be at ground level or comprising a floor surface of a high rise building, or in some embodiments, positioned behind the curtain wall. In such designs, the sill may simply be a horizontal member secured to the vertical mullion. Although not shown in FIG. 1, a head member similar to the horizontal member 10 secures the curtain wall to a concrete slab between floors of a building or other building structures, and a plurality of mullions span between the horizontal member 10 and the head member. The horizontal member 10 is typically formed as an integral aluminum extrusion. The horizontal member 10 also generally includes a channel section 14, an anchoring section 16 disposed interiorly of a channel section 14, and a cover 18.
Still referring to FIG. 1, the channel section 14 and the cover 18 cooperate to secure the panel member 20 to the horizontal member 10. More specifically, the channel section 14 includes a base 14a and two legs 14b and 14c that form a upwardly facing U-shaped channel. A support member 22 rests on the top surface of the base 14a. The exterior leg 14b has a groove 24 proximate the upper end of its interior surface facing the panel member 20, and the interior leg 14c has a support surface 26 proximate the upper end of its interior surface. The cover 18 has a downward projecting leg 28 that engages a groove 30 on the exterior surface of the interior leg 14c. The cover 18 also has two tongues 32, 49, one proximate to each end of the cover 18. The panel member 20 is placed within the channel section 14 on an upper surface of a setting block 34. An exterior and interior gasket 36, 38 are located at the upper end of the exterior and interior legs 14b, 14c. The gaskets 36, 38 operate to hold the panel member 20 in the channel section 14. The setting block 34 is disposed on the top surface of the support member 22. The exterior gasket 36 has a tongue 36a that engages the groove 24 of the exterior leg 14b. The exterior gasket 36 is typically pre-installed in groove 24 of the exterior leg 14b during the manufacture or assembly of the horizontal member 10. The interior gasket 38 has a groove 38a that engages the tongue 32 of the cover 18 and the support surface 26 of the interior leg 14c. The channel section 14 further includes a plurality of support legs 40 below base 14a. 
The anchoring section 16 includes a base 16a, an interior leg 16b, and a plurality of support legs 42 below the base 16a. The base 16a has a plurality of holes 44 spaced along its length for receiving fasteners 46 to secure the horizontal member 10 to the structural support surface 12. The interior leg 16b has a groove 48 for receiving the tongue 49 of the cover 18. The cover 18 stabilizes the interior gasket 38 that presses against the panel member 20 and also conceals the base 16a of the anchoring section 16 so that the fasteners 46 are not visible.
The following technique is typically used to install the panel member 20 of such a curtain wall and is set forth herein for reference purposes. The horizontal member 10 is laid on a shim 56 in the proper position on the concrete slab 12 and is used as a template to drill holes into the concrete slab 12 for each fastener 46. One should note that the shim 56 does not run continuously along the length of the horizontal member 10. Instead, the shim 56 is used at low points of the concrete slab 12 to level the horizontal member 10, if necessary. The horizontal member 10 is then removed from the shim 56, and a hole 50 with a larger diameter is drilled in the place of each of the holes drilled using the horizontal member 10. A structural insert 52 is secured within each of the holes 50 via epoxy or other conventional means. Each insert 52 has an internally threaded hole 54 for receiving fasteners 46. The horizontal member 10 is repositioned on the shim 56 and secured to the concrete slab 12 using fasteners 46. A sealant 58 is continuously disposed on the concrete slab 12 along both the exterior and interior sides of the shim 56. A head member similar to the horizontal member 10 is secured to part of the building structure using the above-described techniques. Vertical mullions are secured between the horizontal member 10 and the head member at appropriate intervals along the curtain wall. The vertical mullions are attached at each side to horizontal members 10. The support member 22 is disposed on the base 14a of the horizontal member 10, and the setting block 34 is disposed on the support member 20. The panel member 20 is then installed from the exterior of the building, typically first being tilted into the channel section of the head member, and then being dropped into the channel section 14 of the horizontal member 10. The cover 18 is installed in the horizontal member 10, and a glazing stop is installed in the head member of the curtain wall. The interior gasket 38 is disposed on the tongue 32 of the cover 18 of the horizontal member 10, and a similar gasket is disposed on the tongue of the glazing stop of the head member.
In most currently used systems, at the junction between horizontal and vertical mullions, the mullion shape often requires special sealing arrangements. For example, the generally U-shaped mullions are not mitered at the intersection of their orthogonal engagement one with the other. The extrusion shape is therefore an issue at the intersection. This is typically found in the channel area of the horizontal member where it does not meet the respective surface of the vertical mullion for sealing purposes. Certain designs therefor incorporate additional sealing members that are secured thereacross. These sealing members are often made of the same or similar material, such as aluminum, for positioning therein.
One such design of a sealing member, a joint plug 200, designed for securement in the region of the intersection of the vertical mullion 202 and the horizontal member 204 is illustrated in FIG. 2. The joint plug 200 is typically a molded or die cut part or an extruded part that is cut-to-size for a particular curtain wall assembly. The joint plug 200 is designed to precisely fit into the void at the region created between the channel 206 and the vertical mullion 202. Sealant 208 is utilized to create a permanent, water-tight seal between the joint plug 200, the vertical mullion 202, and the horizontal member 204. As shown, the insertion of the joint plug 200 creates a stepped-down cavity lower than the bottom surface of the channel 206. The joint plug 200 is a handed piece that may not be utilized in other curtain wall assemblies with intersections of the vertical mullion because the shape of the joint plug 200 is designed specifically for one type of curtain wall system. A handed piece is a non-symmetrical piece that has a specific application (i.e., a different handed piece is needed for each side of a vertical mullion). Also, the joint plug 200 may need to be installed prior to installing exterior face members.
Another such design is set forth and described in co-pending patent application Ser. No. 60/364,880 filed Mar. 13, 2002, assigned to the assignee of the present invention and incorporated herein by reference. As shown therein, the sealing member is made of aluminum. In the particular application as referenced above, incorporated herein by reference, such a metal sealing member has a particular utility that may not be required in certain curtain wall systems. For instance, some curtain wall systems may require additional structural support in the area of the intersection of the horizontal member and the vertical mullion. However, not all curtain wall systems require additional strength at the intersection. The junction between horizontal and vertical mullions does, however, typically require a bulkhead spanning the majority of the open space to provide a surface upon which a sealing compound, such as silicone, may be applied. Even the utilization of metal does not, in and of itself, typically provide a sealed surface when abutting another member. The purpose of applying sealant is typically to prevent and/or control the flow of moisture within the curtain wall systems. The use of waterproof sealant is provided to thereby create a sealed surface to therein deflect the flow of any moisture to an area of the horizontal member where discharge is permitted. Such designs facilitate the drainage of water which has infiltrated the structural members of a curtain wall system and the subject of which is addressed in a number of existing patents including U.S. Pat. Nos. 4,644,717 and 4,773,193 assigned to the Assignee of the present invention.